Piezo-electric crystal apparatus



March 12, 1935. M @SNQS ,994,229

PIEZO ELECTRIC CRYSTAL APPARATUS Filed Feb. 20, 1952 :BEL

MENDE. DSN/OS BY /mw ATTORNEY Patented Mar. 12, 1935 UNITED STAT ES PATENT OFFICE PIEZO-ELECTRIC CRYSTAL APPARATUS Germany Application February 20, 1932, Serial No. 594,223 In Germany March 20, 1931 9 Claims.

This invention relates to improved electrical apparatus wherein the electrodes are conned inside a more or less perfect vacuum, and particularly to Asuch an arrangement whereby the distance between the electrodes is provided with an 4adjustment and is also arranged to increase the distance between the electrodes las the temperature increases.

An object of this invention is to simplify and improve the construction of variable electric apparatus having a fixed and a variable electrode contained Within a vacuum.

Another object is to provide a new and improved form of piezo-electric crystal holder.

A feature of this invention is an improved arrangement for stabilizing the natural period of electrical circuits containing piezo-electric crystals.

Another feature of this invention is the improved arrangement whereby the electrodes can be utilized as a variable condenser which can be employed to change the tuning of an electrical circuit.

According to the present invention, the spacer body consists of a liquid, preferably of mercury, and on the top of the same, or inside the same, there floats a body xedly connected with an electrode.

Inasmuch as liquids, as a general rule, possess a higher coeiiicient of expansion, this fact alone will tend to make the change in distance or spacing larger than in the case of a solid spacer body. In addition, it is possible to insure any desired large iniluence of the temperature liuctuations upon the height of the liquid level if the liquid is placed within a container tapering towards the top, for instance, in a tubular extension,

In the accompanying drawing, Figure 1 illustrates an arrangement embodying the principles of the present invention, and Figure 2 illustrates a cross-section View of the arrangement of Figure l along the line XX.

One particular embodiment of the arrangement according to the invention is illustrated in the drawing, where l denotes a setting knob, 2 a screw-threaded brass bolt attached thereto, 3 a oat, preferably consisting of glass, 4 an adjustable electrode adapted to be set by screwing its screw-threaded stem more or less far onto the said bolt 2, 5, the stationary electrode, 6 the crystal, 7 a metal chamber or vessel having a wide base part 8 and a narrower tubular extension 9; 10 denotes mercury, 1l are supporting edges of the float whereby the bolt 2 is kept perpendicular in position, 12 a glass vessel or hood with pump stem, and 13, 13, the current supply leads of the electrodes. The bodies and 7 are united together by soldering or else they are hermetically .cemented together.

The larger the volume of the base part 8 is chosen, the greater will be the fluctuations in the surface level of the mercury and thus the interelectrode distance change per degree C.

By the adjusting knob l, when the hood 12 is removed, the desired distance between the electrodes is obtained. Thereupon the hood is replaced, the electrode 5 is cemented, and the interior of the crystal holder is evacuated.

I claim:

l. Piezo-electric crystal apparatus comprising an evacuated vessel containing a xed electrode and a movable electrode, a piezo-electric crystal interposed between said electrodes, a liquid responsive to temperature variations, and a floating support for said movable electrode, said floating support being arranged to be upheld by said liquid so as to alter the space between said electrodes.

2. An arrangement as described in claim 1 characterized in this, that said liquid is mercury.

3. A piezo-electric crystal holder comprising an evacuated vessel, a plurality of spaced electrodes arranged therein, a, fluid responsive to temperature variations located in a chamber beneath said evacuated vessel, and means to vary the spacing between said electrodes in accordance with the temperature variations of said fluid.

4. Vacuous electrical apparatus comprising an evacuated vessel, a plurality of spaced electrodes arranged therein, a fluid responsive to temperature variations located in a chamber beneath said evacuated vessel, and means to vary the electrical capacity between said electrodes in accordance with the temperature variation of said fluid.

5. A piezo-electric crystal holder comprising an evacuated vessel containing a xed electrode and a movable electrode, a piezo-electric crystal interposed between said electrodes, a liquid responsive to temperature variations and a floating support for said movable electrode, said floating support having adjusting means and arranged to be upheld by said liquid so as to alter the space between said electrodes.

6. A piezo-electric crystal holder comprising a vessel containing a Xed electrode and a movable electrode, a piezo-electric crystal interposed between said electrcdes, a liquid responsive to temperature variations contained in a chamber located below said vessel, and a oating support for said movable electrode, said floating support having adjusting means and arranged to be upheld by said liquid so as to alter the space between said electrodes.

7. A piezo-electric crystal holder comprising a vessel containing a xed electrode having a central aperture and a movable electrode, a piezoelectric crystal interposed between said electrodes, a liquid responsive to temperature variations contained in a chamber located below said vessel, and a floating support for said movable electrode, said floating support having an upward extending rod passing through the aperture in said fixed electrode and arranged toV be upheld by said liquid so as to alter the space between said electrodes. Y

8. A piezo-electric crystal holder comprising an insulating vessel containing a xed electrode having a central aperture and a movable electrode, a piezo-electric crystal interposed between said electrodes, a liquid responsive to temperature variations contained in a metallic chamber located below said insulating vessel, and a floating support for said movable electrode, said floating support having an upward extending threaded rod having an adjusting knob and passing through the aperture in said xed electrode and arranged to be upheld by said liquid so as to alter the space between said electrodes.

9. A piezo-electric crystal holder comprising an evacuated vessel containing a xed electrode having a central aperture and a movable electrode, a piezo-electric crystal interposed between said electrodes, a liquid responsive to temperature variations contained in a chamber located below said evacuated vessel and having a substantially Wide base portion and a substantially narrow uprising tubular extension, a floating support having an upward extending rod for securing said movable electrode, said oating support located in said narrow uprising tubular extension, said upward extending rod passing through the aperture in said xed electrode and arranged to be upheld by said liquid so as to alter the space between said electrodes.

MENDEL OSNOS. 

